The stimulating action of the dinitrophenols on the oxygen consumption of cells and tissues is generally thought to reside in an acceleration of metabolic processes involving4 primarily the oxidation of carbohydrate. Dodds and Greville1 showed that the extra oxygen uptake induced by 4,6-dinitro-o-cresol (DNC) in kidney slices had a R.Q. of 1. Ehrenf est and Ronzoni2 demonstrated an increased oxidation of carbohydrate in yeast treated with dinitrophenol (DNP). Later3 they demonstrated that DNP was without effect in iodoacetate poisoned muscle. Clowes and Krahl4 showed that the R.Q. of sea urchin eggs in the presence of DNC remained at the level characteristic of untreated eggs, viz., 0.93 to 0.95. Field and Tainter5 present data to show that the stimulation of respiration in yeast by DNC is maximal in the presence of glucose.In view of the fact that most of the work dealing with the effects of dinitrophenols has been done on biological systems whose normal fuel is in the main carbohydrate, it seems advisab...